Fuel from corn
Years ago, the machine that was most nearly capable of reproducing itself was the lathe. Nowadays, it is obviously the computer.
That raises an interesting question about the so-called "renewable" energy resources. Trees and other plants reproduce themselves, to be sure. But who has ever used solar energy to manufacture solar collectors, thereby to collect more solar energy? Who has ever used a solar furnace to produce plate glass for heat collectors? Who has ever used photovoltaics to manufacture photovoltaic collectors?
And has anybody at Archer Daniels Midland ever used ethanol from corn to distill ethanol from corn mash? Not a chance. Read on.
We make up for it in quantity
That was a long time ago, so I recently surfed the net to find manufacturers of distillation equipment for more recent data. I found one who seemed willing to communicate; he gave me the names and addresses of four such factory owners. I wrote personal letters to all of them asking for information about distillation efficiency, but none responded.
Their reticence is well founded. Pimentel  provides us with the data. Overall (farming, distillation), it takes 129,600 BTU to produce a gallon of EtOH, but the energy value of a gallon of EtOH is only 76,000 BTU. In SI units [conversions in footnote 3]: it takes 45.7 MJ to produce a kilogram of EtOH, but the energy value of that kilogram of EtOH is 26.8 MJ.
There is thus a net energy loss of about 54,000 Btu for every gallon (18.9 MJ for every kilogram) of EtOH produced. Unlike the old joke about the tailor who claims he loses money on every suit, but stays in business by "making up for it in quantity," there is no deception here. It's a losing proposition.
What the Green Gang lacks in rationality, they make up for in quantity. So what if an investment of 129,600 BTU of energy yields only 76,000 BTU? Every year, the federal government subsidizes American farmers to produce a billion gallons of EtOH at that rate, needlessly throwing away the energy equivalent of nearly a half-billion gallons of gasoline while doing so.
But, for all the Political Correctness, the scam produces only about one percent of the EtOH used in gasoline.
 Howard C. Hayden, "Solar Energy: How Bright the Prospect?" The Science Teacher 48, pp. 17-22 (Apr. 1981).
 David Pimentel, "Energy and Dollar Costs of Ethanol Production with Corn," Hubbert Center Newsletter #98/2 (Apr. 1998)
 EtOH: density = 789.3 kg/m3; 1 gal = 231 in3; 1 inch = 0.0254 m; ==> 1 gal of EtOH contains 2.99 kg; 1 BTU = 1054 J; 1 MJ = 106 J.
To main Energy Advocate Index
The Energy Advocate